Many people choose a pen as a gift for their relatives or friends. The barrel and cap of gift pens are usually made from a noble metal. Sweat may adhere to the pen barrel and the pen cap. The sweat can corrode the noble metal and degrade the appearance of the pen over time. Therefore, if the owner of the pen wants to keep the appearance of the pen unchanged, for example, to represent that family love or friendship will never fade, the pen owner's only choice is to keep the pen as merely an ornament. Therefore, the pen's utility as a writing instrument is largely reduced.
Realizing the problem with pens made from metal, pens used as gifts may now include granular ornaments. The pen barrel and pen cap can be made of a transparent plastic material to display the granular ornaments. A cavity provided within the pen barrel and/or pen cap is filled with the granular ornaments. Granular ornaments may include crystals, diamonds, and gems, among other materials. The pen has both an appealing appearance and is useful. With conventional processes, the operation of filling the cavity of the pen cap with granular ornaments is performed manually. The process involves tapping the pen on the worktable to create vibrations in order to fill the cavities with the granular ornaments. However, due to limitations of manually tapping the pens on the worktable, the granular ornaments may become unevenly distributed. Therefore, the appearance of the pen suffers, and substantial gaps may appear among the granular ornaments after using the pen. Additionally, the granular ornaments may shake or come loose once inside the pen cap, scratching the transparent material. This results in damage to the pen cap and an unappealing appearance after a period of extended use.